Bio-substance assay methods employing a solid phase such as a polystyrene plate or magnetic particles onto which a target substance is to be adsorbed are widely employed in clinical tests, diagnostic agents, and the like. Generally, such a bio-substance is detected through enzymatic coloration or fluorescence or chemical luminescence. In either detection method, biomolecules present in a serum sample, secondary antibody, protein and lipid contained in a coloration substrate, and other related substances are adsorbed non-specifically onto a solid phase, a container, an instrument, or the like, and the adsorbed substances cause noise in the assay, thereby problematically impairing the sensitivity of the assay.
In one mode for solving the problem, the surface of a solid phase, a container, an instrument, or the like is treated with a bio-origin substance such as albumin, casein, or gelatin, in order to prevent non-specific adsorption of protein, lipid, and the like.
However, the aforementioned bio-origin substance exhibits insufficient non-specific adsorption inhibitory effect, and a bio-contamination-related problem such as BSE may occur.
Thus, there is demand for development of a chemically synthesized surface-hydrophilizing agent. Hitherto, there have been proposed, as the surface-hydrophilizing agent, a specific polymer having a polyoxyethylene chain (Patent Documents 1 and 2) and a specific methacrylic copolymer (Patent Document 3).